diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index f23bbf0e1f..788b26446d 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -165,8 +165,8 @@ class FederationSender(object):
                     and not self._transaction_manager.deprioritise_transmission
                 ):
                     logger.warning(
-                        "Event processing loop is getting behind: deprioritising "
-                        "transaction transmission"
+                        "Event queue is getting behind: deprioritising transaction "
+                        "transmission"
                     )
                     self._transaction_manager.deprioritise_transmission = True
 
diff --git a/synapse/federation/sender/per_destination_queue.py b/synapse/federation/sender/per_destination_queue.py
index b890aaf840..69a6f47b7b 100644
--- a/synapse/federation/sender/per_destination_queue.py
+++ b/synapse/federation/sender/per_destination_queue.py
@@ -15,6 +15,7 @@
 # limitations under the License.
 import datetime
 import logging
+import random
 
 from prometheus_client import Counter
 
@@ -36,6 +37,8 @@ from synapse.util.retryutils import NotRetryingDestination, get_retry_limiter
 # This is defined in the Matrix spec and enforced by the receiver.
 MAX_EDUS_PER_TRANSACTION = 100
 
+DEPRIORITISE_SLEEP_TIME = 10
+
 logger = logging.getLogger(__name__)
 
 
@@ -191,8 +194,13 @@ class PerDestinationQueue(object):
             while True:
                 if self._transaction_manager.deprioritise_transmission:
                     # if the event-processing loop has got behind, sleep to give it
-                    # a chance to catch up
-                    yield self._clock.sleep(2)
+                    # a chance to catch up. Add some randomness so that the transmitters
+                    # don't all wake up in sync.
+                    sleeptime = random.uniform(
+                        DEPRIORITISE_SLEEP_TIME, DEPRIORITISE_SLEEP_TIME * 2
+                    )
+                    logger.info("TX [%s]: sleeping for %f seconds", sleeptime)
+                    yield self._clock.sleep(sleeptime)
 
                 # We have to keep 2 free slots for presence and rr_edus
                 limit = MAX_EDUS_PER_TRANSACTION - 2